Measure by Measure: Resting Heart Rate Across the 24 Hour Cycle.

Background: Photoplethysmography (PPG) sensors, typically found in wrist-worn devices, can continuously monitor heart rate (HR) in large populations in real-world settings. Resting heart rate (RHR) is an important biomarker of morbidities and mortality, but no universally accepted definition nor measurement criteria exist. In this study, we provide a working definition of RHR and describe a method for measurement of RHR recorded using PPG derived from wristband measurement across a 24-hour cycle. Methods: 433 healthy subjects wore a wrist device that measured activity and HR for up to 3 months. HR during inactivity was recorded and the duration of inactivity needed for HR to stabilise was ascertained. We identified the lowest HR during each 24-hour cycle (true RHR) and examined the time of day or night this occurred. The variation of HR during inactivity through the 24-hour cycle was also assessed. The sample was also subdivided according to daily activity levels for subset analysis. Findings: Adequate data was obtained for 19,242 days and 18,520 nights. HR stabilised in most subjects after 4 minutes of inactivity. Mean (SD) RHR for the sample was 54.5 (8.0) bpm (day) and 50.5 (7.6) bpm (night). RHR values were highest in the least active group (lowest MET quartile) . A circadian variation of HR during inactivity was confirmed, with the lowest values being between 0300 and 0700 hours for most subjects. Interpretation: RHR measured using a PPG-based wrist-worn device is significantly lower at night than in the day, and a circadian rhythm of HR during inactivity was confirmed. Since RHR is such an important health metric, clarity on the definition and measurement methodology used is important. A minimum rest time of 4 minutes provides a reliable measurement of HR during inactivity and true RHR in a 24-hour cycle is best measured between 0300 and 0700 hours. Funding: This study was funded by Google.

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Season-Long Heart-Rate Variability Tracking Reveals Autonomic Imbalance in American College Football Players

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2020-0801 ◽

2021 ◽

pp. 1-10

Author(s):

Andrew A. Flatt ◽

Jeff R. Allen ◽

Clay M. Keith ◽

Matthew W. Martinez ◽

Michael R. Esco

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

College Football ◽

Time Of Day ◽

Football Players ◽

Resting Heart Rate ◽

Autonomic Imbalance ◽

Natural Logarithm ◽

Competitive Season ◽

Red Flag

Purpose: To track cardiac-autonomic functioning, indexed by heart-rate variability, in American college football players throughout a competitive period. Methods: Resting heart rate (RHR) and the natural logarithm root mean square of successive differences (LnRMSSD) were obtained throughout preseason and ∼3 times weekly leading up to the national championship among 8 linemen and 12 nonlinemen. Seated 1-minute recordings were performed via mobile device and standardized for time of day and proximity to training. Results: Relative to preseason, linemen exhibited suppressed LnRMSSD during camp-style preparation for the playoffs (P = .041, effect size [ES] = −1.01), the week of the national semifinal (P < .001, ES = −1.27), and the week of the national championship (P = .005, ES = −1.16). As a combined group, increases in RHR (P < .001) were observed at the same time points (nonlinemen ES = 0.48–0.59, linemen ES = 1.03–1.10). For all linemen, RHR trended upward (positive slopes, R2 = .02–.77) while LnRMSSD trended downward (negative slopes, R2 = .02–.62) throughout the season. Preseason to postseason changes in RHR (r = .50, P = .025) and LnRMSSD (r = −.68, P < .001) were associated with body mass. Conclusions: Heart-rate variability tracking revealed progressive autonomic imbalance in the lineman position group, with individual players showing suppressed values by midseason. Attenuated parasympathetic activation is a hallmark of impaired recovery and may contribute to cardiovascular maladaptations reported to occur in linemen following a competitive season. Thus, a descending pattern may serve as an easily identifiable red flag requiring attention from performance and medical staff.

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EFFECT OF DEFINITION OF RESTING HEART RATE ON APPARENT ACTIVITY LEVELS OF PRE-SCHOOL CHILDREN

Medicine & Science in Sports & Exercise ◽

10.1097/00005768-199905001-01099 ◽

1999 ◽

Vol 31 (Supplement) ◽

pp. S231

Author(s):

N Logan ◽

J Reilly ◽

S Grant ◽

J Paton

Keyword(s):

Heart Rate ◽

School Children ◽

Activity Levels ◽

Resting Heart Rate ◽

Definition Of

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Elevated resting heart rate is associated with increased radiographic severity of knee but not hand joints

Scientific Reports ◽

10.1038/s41598-021-03237-4 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Sung-Eun Choi ◽

Haimuzi Xu ◽

Ji-Hyoun Kang ◽

Dong-Jin Park ◽

Sun-Seog Kweon ◽

...

Keyword(s):

Heart Rate ◽

Knee Joint ◽

Musculoskeletal Diseases ◽

Smoking Status ◽

Chronic Obstructive ◽

Activity Levels ◽

Resting Heart Rate ◽

Radiographic Severity ◽

Hand Joints ◽

Risk Of Cancer

AbstractAlthough the resting heart rate (RHR) predicts the clinical outcomes of cardiovascular disease, chronic obstructive lung disease, diabetes mellitus, and the risk of cancer, its role in patients with musculoskeletal diseases, such as osteoarthritis (OA), remains unclear. We explored the association of the RHR with the extents of radiographic changes in the knees and hands of 2369 subjects from the Dong-gu Study. The radiographic hand and knee joint findings were graded semi-quantitatively; we calculated total hand and knee joint scores. Multiple linear regression was performed to examine the associations between the RHR and the radiographic characteristics of these joints. For the knee joints, the RHR was associated positively with the total (p < 0.01), osteophyte (p < 0.01), joint space narrowing (JSN; p < 0.01), and tibial attrition (p = 0.02) scores after adjustment for age, sex, body mass index, smoking status, alcohol consumption, educational and physical activity levels, and comorbidities. For the hand joints, the RHR was associated positively with the JSN (p = 0.01) and subchondral cyst (p < 0.01) scores after such adjustment. The RHR was not associated with the total, osteophyte, sclerosis, erosion, or malalignment score for the hand joints. This study is the first to reveal an association between the RHR and the radiographic severity of knee, but not hand, OA.

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Heart Rate Variability in Sport Performance: Do Time of Day and Chronotype Play A Role?

Journal of Clinical Medicine ◽

10.3390/jcm8050723 ◽

2019 ◽

Vol 8 (5) ◽

pp. 723 ◽

Cited By ~ 11

Author(s):

Jacopo Antonino Vitale ◽

Matteo Bonato ◽

Antonio La La Torre ◽

Giuseppe Banfi

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Nervous System ◽

Autonomic Nervous System ◽

Time Course ◽

Sport Performance ◽

Time Of Day ◽

Activity Levels ◽

Autonomic Nervous ◽

Invasive Method

A reliable non-invasive method to assess autonomic nervous system activity involves the evaluation of the time course of heart rate variability (HRV). HRV may vary in accordance with the degree and duration of training, and the circadian fluctuation of this variable is crucial for human health since the heart adapts to the needs of different activity levels during sleep phases or in the daytime. In the present review, time-of-day and chronotype effect on HRV in response to acute sessions of physical activity are discussed. Results are sparse and controversial; however, it seems that evening-type subjects have a higher perturbation of the autonomic nervous system (ANS), with slowed vagal reactivation and higher heart rate values in response to morning exercise than morning types. Conversely, both chronotype categories showed similar ANS activity during evening physical tasks, suggesting that this time of day seems to perturb the HRV circadian rhythm to a lesser extent. The control for chronotype and time-of-day effect represents a key strategy for individual training schedules, and, in perspective, for primary injury prevention.

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Association between 1-mile run times in training and selected predictors: A case study

International Journal of Sport Exercise and Health Research ◽

10.31254/sportmed.4109 ◽

2020 ◽

Vol 4 (1) ◽

pp. 37-40

Author(s):

John Hart ◽

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Regression Analysis ◽

Linear Regression ◽

Time Of Day ◽

Relative Strength ◽

Resting Heart Rate ◽

Outdoor Temperature ◽

Strength Of Association

Runners have an interest in what variables might help them achieve faster run times. In this case study of an individual runner, six predictors are compared to his 1-mile run times over a 1-year period. The six predictors consisted of run sessions (1, 2, etc), outdoor temperature, outdoor humidity, time of day that run began, resting heart rate (HR) on day of run, and heart rate variability also on day of run. Predictors that showed statistically significant correlations were included in multiple linear regression to compare relative strength of association with run times. Two predictors qualified for regression analysis: run session and HR. Both continued to show statistically significant associations in regression.

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Investigation of an estimate of daily resting heart rate using a consumer wearable device

10.1101/19008771 ◽

2019 ◽

Author(s):

Allison Russell ◽

Conor Heneghan ◽

Subbu Venkatraman

Keyword(s):

Heart Rate ◽

Low Cost ◽

Circadian Variation ◽

Wearable Device ◽

Clinical Settings ◽

Resting Heart Rate ◽

Optical Technology ◽

Measure Heart Rate ◽

Resting Period ◽

Lying Down

AbstractResting heart rate is accepted as a valid overall indicator of cardiovascular risk and is a low-cost easy-to-measure metric that can be collected in both home and clinical settings. Wearable devices such as smartwatches and trackers can measure heart rate continuously using optical technology. This study reports initially on the agreement between the resting heart rate reported by a wearable device (Fitbit Charge HR and Fitbit Blaze) and a chest-based consumer electrocardiogram (Polar H7). In 45 subjects, the reported resting heart rates agreed within 0.89 bpm over a resting period of 5 mins. The same device and algorithm was then used in a population of 168 subjects (45.9± 15.6 yrs) who were asked to collect their resting heart rate for four days under seven different conditions and times (at wake sitting/lying down, pre-breakfast, pre-lunch, pre-dinner, and before bed sitting/lying down). The reported values were compared with the Daily Resting Heart Rate (DRHR) reported by the wearable device. The measurement lying down before wake were closest to the DRHR (mean error of 0.0 bpm with a 25-75th percentile spread of ±3.5bpm. There was a significant circadian variation in the reported resting heart rate across subjects, with the highest values reported in the middle of the day. Within individual subjects, the median standard deviation of heart rate at rest was 3-5bpm even measured under nominally similar conditions over four days.

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Regional Frontal Lobe Response Magnitudes During Affective Shifting Covary With Resting Heart Rate Variability in Healthy Volunteers

Journal of Psychophysiology ◽

10.1027/0269-8803/a000166 ◽

2016 ◽

Vol 30 (4) ◽

pp. 165-174 ◽

Cited By ~ 3

Author(s):

Ryan Smith ◽

John J.B. Allen ◽

Julian F. Thayer ◽

Richard D. Lane

Keyword(s):

Heart Rate ◽

Heart Rate Variability ◽

Healthy Subjects ◽

Emotional Reactivity ◽

Bold Signal ◽

Resting Heart Rate ◽

Functional Magnetic Resonance ◽

Absolute Value ◽

Cardiac Vagal Control ◽

Resting Heart Rate Variability

Abstract. We hypothesized that in healthy subjects differences in resting heart rate variability (rHRV) would be associated with differences in emotional reactivity within the medial visceromotor network (MVN). We also probed whether this MVN-rHRV relationship was diminished in depression. Eleven healthy adults and nine depressed subjects performed the emotional counting stroop task in alternating blocks of emotion and neutral words during functional magnetic resonance imaging (fMRI). The correlation between rHRV outside the scanner and BOLD signal reactivity (absolute value of change between adjacent blocks in the BOLD signal) was examined in specific MVN regions. Significant negative correlations were observed between rHRV and average BOLD shift magnitude (BSM) in several MVN regions in healthy subjects but not depressed subjects. This preliminary report provides novel evidence relating emotional reactivity in MVN regions to rHRV. It also provides preliminary suggestive evidence that depression may involve reduced interaction between the MVN and cardiac vagal control.

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